Method getSampleBlock

src/Interpreters/InterpreterSelectWithUnionQuery.cpp:275–290

InterpreterSelectWithUnionQuery::~InterpreterSelectWithUnionQuery() = default;

Block InterpreterSelectWithUnionQuery::getSampleBlock(const ASTPtr & query_ptr_, ContextPtr context_, bool is_subquery)
{
    auto & cache = context_->getSampleBlockCache();
    /// Using query string because query_ptr changes for every internal SELECT
    auto key = queryToString(query_ptr_);
    if (cache.find(key) != cache.end())
    {
        return cache[key];
    }

    if (is_subquery)
        return cache[key]
            = InterpreterSelectWithUnionQuery(query_ptr_, context_, SelectQueryOptions().subquery().analyze()).getSampleBlock();
    else
        return cache[key] = InterpreterSelectWithUnionQuery(query_ptr_, context_, SelectQueryOptions().analyze()).getSampleBlock();
}


void InterpreterSelectWithUnionQuery::buildQueryPlan(QueryPlan & query_plan)